In commerce, many goods are sold as bulk materials. The term “bulk materials” refers to items obtained, transported, used, stored, or handled in a group, non-limiting examples of which include grain, wheat, vegetables, tea, spices, flavorings, peanuts, coffee beans, soybeans, and other agricultural products; manufactured food products (including human food and pet food products); and pharmaceutical or other health products such as multivitamins and supplements. Each example is an item that can be broken down into individual units and grouped with numerous others of its kind for packaging or shipment, or grouped with others of its kind and used as food ingredients. In a production plant, bulk and other materials are frequently sent along a conveyor as part of the production process. Often, the bulk materials are in the form of particulates. In some instances, the materials which are sampled are liquid, whereby a portion of the liquid is separated and transported into the collection device.
There is a need to sample bulk and other materials to determine if they contain any matter that causes injury, disease, or irritation if inhaled or ingested by a person or absorbed through the skin, or matter that creates a risk of combustion or explosion, either by itself or in contact with other matter. Such matter is characterized in different ways, and depending on its nature may be referred to variously as contaminants, adulterants, pathogens, viruses, bacteria, microorganisms, fungi, toxins, toxic chemicals, and pollutants. For brevity, such examples of matter set forth in this paragraph are referred to herein as “contaminants.”
Alternatively, a need exists to sample materials to determine if they contain matter that is desirable and beneficial, i.e., which is supposed to be present. Such substances include, again by way of illustration only, an additive used to enhance a manufacturing process related to a particular commodity; or matter incorporated with a particular commodity providing beneficial, nutritional, or therapeutic effects, such as proteins, nanoparticles, and additives. For brevity, all such substances contemplated by this paragraph are referred to, individually and collectively, as “additives.”
In the past, various attempts have been made to sample materials, for the purpose of testing to see if contaminants or additives are present in the bulk materials. In some instances, the materials are related to food, while in other contexts this sampling has been performed on non-food bulk materials. The present embodiments are not limited to the type of materials (bulk or otherwise) which they are practiced upon.
In this sense, sampling the bulk materials, or “taking a sample,” involves separating a large quantity of bulk materials into a very small portion that is taken out of production and used for sampling, from the remainder of the bulk materials. Airflow separators are used in many applications to separate particulate matter as a means of collecting a sample, where separation occurs based on differences in size or density (or both) of particles making up the bulk materials. Cyclonic separators, also referred to as cyclones, are a type of airflow separator, having a geometry which facilitates a cyclonic airflow within the chamber as the airflow is drawn into and through it. Other airflow separators produce different kinds of air movement, including but not limited to axial flow, laminar flow, and turbulent flow. Although the term cyclonic separator is used somewhat more frequently herein than some other types of airflow separators, embodiments are not limited to cyclonic separators.
Airflow separators are usually operated by a fan run at constant speed that draws air into and through the device, as running them at constant speed is important for maintaining consistency of performance. As air enters and travels through the device, by the action of the fan, the resulting airflow transports some of the particles away from the sampling point and into the cyclone via a conduit. Generally, cyclonic separators operate based on a precise flow determined by the physical design characteristics of the cyclone and the requirements for sample separation and collection, in order to maintain a constant and precise flow of air and matter through the cyclone that increases sampling efficiency.
Conventional airflow separators are known generally to those skilled in the art. These include, but are not limited to, collectors, separators, wetted wall cyclones, and multi-stage configurations, all of which transport material under a flow of air or gas. Such airflow separators handle a wide range of products, including but not limited to particles, aerosolized particles, liquids, aerosolized liquids, biological material, and metals, any of which can be dispersed in air or other gases.
In most cases when contaminants are present in bulk materials, the contamination is localized, rather than diffuse, i.e., spread throughout the entirety of the bulk materials. Thus, although various approaches have been tried before with respect to sampling to determine contamination, the results have been poor because usually the approach involves “grab sampling” or some other technique that obtains a sample only at intervals. In some cases, the protocol calls for a person to manually obtain a sample at some predetermined interval. Other times, the sampling process is automated so that a machine obtains the sample, for example by pneumatic force or suction that redirects a portion of bulk or other materials moving along a conveyor or stored in a bin, or otherwise going through production steps. Again, though, conventional sampling performed through automation is limited just like manual sampling, in that it is done at discrete intervals. Also, sample volumes collected through automation are usually fixed and, therefore, not subject to adjustment. Consequently, localized contamination is detected only if the contamination passes the sampling point at the precise interval when the sample is taken.
Although airflow separators are known, problems and limitations are still encountered in their use. For example, the performance of cyclonic separators depends on maintaining a precise and constant flow of air and matter through the device at a preset, constant fan speed. However, these constants might not be compatible with the sampling flow requirements of a particular operation, in which sampling rate may be lower than the optimum cyclone flow. Stated differently, one operation might want to fill a sampling vessel every hour, while another might only fill the sampling vessel once or twice during an eight hour shift. Consequently, changing (raising or lowering) the total flow within this type of airflow separator to an optimum value for sampling might negatively impact the cyclonic efficiency and performance, for example if the fan speed were turned lower to reduce the rate at which sample is being collected. The problem is that when one changes flow through the total system by varying fan speed, or changing the restriction of air movement, for example, it can have negative impact on the overall performance of the cyclone.
Accordingly, there is significant need for continuous automated sampling, where the sampling rate can be varied even though the fan speed remains constant.